In the manufacturing process of semiconductor devices, the coating, light exposing and imaging of photoresist layer are necessary technological steps for the formation of patterns on devices as shown in FIG. 1. The photoresist layer to be ion implanted on the substrate of ground layer must be removed after imaging while the photoresist layer not to be ion implanted on the substrate must be preserved. After ion implantation, the photoresist layer must be removed, and then annealing is performed. Until now a two-step method has been used to remove the photoresist layer. In the first step, plasma etching is employed to remove the most part of the photoresist layer and then a wet etching/washing technique is employed to remove and wash off the remaining photoresist layer. In the plasma etching step, a very strong ashrizing machine must be used. In the second step, a washing solution of strong chemical activity is necessary, which is generally toxic and flammable. In the plasma etching step, a fluorine containing compound is used. In the subsequent wet etching/washing technique, the generally used chemical constituents are an organic solvent and a fluoride in high concentration. The wet etching/washing must take place in a heated environment and the time is long because during doping step after ion bombardment the polymer in photoresist layer becomes stiff and, therefore, its solubility is lowered, thus the wet etching/washing time must be sufficiently long. U.S. Pat. Nos. 6,777,380, 6,274,537, 6,692,903 etc all use a two-step method said above. Moreover, the existing method sometimes cannot guarantee complete removal of photoresist layer.
In a word, this technology is of high cost and low yield and is complicated by problems of environment and remaining photoresist layer. It is, therefore, urgently necessary to propose a new technology for cleaning the photoresist layer.